Such a bending device comprises a rotating bend die or matrix and a vice facing the matrix. Said vice is mounted on a bend arm and clamps a section of the workpiece immediately after the section to be bent, according to a feeding direction of the workpiece. The bending device comprises also a pressure die or countermatrix, which is located directly before the clamped section of the workpiece, the countermatrix being not rotating together with the bend arm. When the workpiece is drawn around the matrix, the countermatrix moves together with the workpiece, to withstand the radial opposite forces of the workpiece. In addition to the countermatrix, a die able to prevent wrinkles is mounted on the not rotating part of the bending machine opposite the countermatrix, and is adjustable in its position with respect to the matrix configuration. The not rotating part of the bending machine, which can be of any known kind, e.g. being shaped as both a bench or a longitudinal member, with mandrel or without, is not relevant for the present invention and will not be described here.
Some problems that are met in known bending machines concern first of all the construction of the countermatrix unit which must be very robust, and then bulky, to withstand the opposite forces exerted by a workpiece being worked. In fact, construction deficiency of the countermatrix unit creates working defects, such as not uniform radius of a bend and not correct dimensions of the worked piece. For this reason such a construction needs a special design, which contributes to raise costs of bending machines.
Further, in known bending machines the die able to prevent wrinkles is driven by its own drive control to be correctly positioned with respect to the workpiece. Such a drive control of the die able to prevent wrinkles is located opposite a drive control which is used to position the countermatrix. This requests that an operator has troublesomely to move around the machine, to position both the die able to prevent wrinkles and the countermatrix according to the piece to be bent.